Localized electronic states induced by oxygen vacancies on anatase TiO2 (101) surface

A theoretical study about the influence of surface oxygen vacancies on the structural and electronic properties of anatase TiO2 (101) surface is presented. Calculations were performed within the density functional theory using the self-consistent Hubbard U correction to take into account the electron repulsion increase and the localization of additional electrons in the reduced anatase. The oxygen vacancies yield surface Ti3 + species, producing localized electronic states in the energy gap of the anatase TiO2 (101). By increasing the oxygen vacancies, the electron concentration also increases in the energy gap region and some of the localized electronic states approaching the conduction band minimum. Thus reduced anatase TiO2 (101) behaves as an n-type semiconductor, and the surface Ti3 + species presence improves its photocatalytic properties.